Bad front bearing?
11-11-2007, 10:14 PM
#1
Thread Starter
Bad front bearing?
I was racing my KMP Critical Mass Sea Fury with a YS 110 FZ today in Sacramento and the cage workers on the south pylon reported hearing a strange noise coming from my plane.
Fearing flutter or some other structural issue I inspected the airframe and found nothing out of the ordinary.
In the next race I was able to hear this sound myself on the front straight and I can only describe it as a squealing type noise.
It reminded me of the sound you might get if the spinner backplate was to rub on a fiberglass cowl.
It did not make this noise for the full race. And I was able to complete the race with no difficulty.
Power output did not seem to suffer.
The cage workers said the noise was worse when I was pulling the turn hard, as compared to when I was able to make a smoother turn.
I pulled the plug and twisted the thrust washer and think I am feeling a less than perfect bearing on the crank.
I am guessing that under load in the turns the gyroscopic forces involved are working this bearing to the point that it is making this sound in it's present state.
Has anyone else had this happen? I mean a noisy bearing you could hear in flight?
Fearing flutter or some other structural issue I inspected the airframe and found nothing out of the ordinary.
In the next race I was able to hear this sound myself on the front straight and I can only describe it as a squealing type noise.
It reminded me of the sound you might get if the spinner backplate was to rub on a fiberglass cowl.
It did not make this noise for the full race. And I was able to complete the race with no difficulty.
Power output did not seem to suffer.
The cage workers said the noise was worse when I was pulling the turn hard, as compared to when I was able to make a smoother turn.
I pulled the plug and twisted the thrust washer and think I am feeling a less than perfect bearing on the crank.
I am guessing that under load in the turns the gyroscopic forces involved are working this bearing to the point that it is making this sound in it's present state.
Has anyone else had this happen? I mean a noisy bearing you could hear in flight?
11-11-2007, 10:47 PM
#2
Senior Member
RE: Bad front bearing?
Yes its time right now to change it..and I mean right now. Don't continue to run the engine if it is making this noise. Front and rear bearings are the normal change out. Its really rare thata front bearing goes...usually its the rear bearing.
But if its making this noise it will be coming apart soon. Very soon If it has not already.
The bearings need to be changed.
Troy Newman
Team YS
But if its making this noise it will be coming apart soon. Very soon If it has not already.
The bearings need to be changed.
Troy Newman
Team YS
11-12-2007, 01:40 AM
#4
RE: Bad front bearing?
Tommy,
Another possible source for the squeal would be the panic your plane had coming out of the south turn when it saw the teeth on my P-40 coming up strong on your 6.
Two breakouts and had to pack it in early....................... all things considered, still a great day of racing.
See you in 2 weeks for the Outlaws.
Skids
Another possible source for the squeal would be the panic your plane had coming out of the south turn when it saw the teeth on my P-40 coming up strong on your 6.
Two breakouts and had to pack it in early....................... all things considered, still a great day of racing.
See you in 2 weeks for the Outlaws.
Skids
?
11-12-2007, 01:11 PM
#7
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RE: Bad front bearing?
Troy,
As a general rule, how often should the rear bearing be replaced? I know there are a myriad of varying factors, but I am thinking more in the lines of "preventative maintenance". And, would it be prudent to replace the bearings with high performance ceramic bearings?
In any case, my relevant factors are: YS110 FZ, 30% Heli Fuel, Funtana 90, 16X6 APC Prop, primarily pattern with a little bit of aerobatics.
TIA
Steve
As a general rule, how often should the rear bearing be replaced? I know there are a myriad of varying factors, but I am thinking more in the lines of "preventative maintenance". And, would it be prudent to replace the bearings with high performance ceramic bearings?
In any case, my relevant factors are: YS110 FZ, 30% Heli Fuel, Funtana 90, 16X6 APC Prop, primarily pattern with a little bit of aerobatics.
TIA
Steve
11-12-2007, 06:07 PM
#8
Senior Member
RE: Bad front bearing?
I usually replace bearings about every 300 flights. This is when I do the ring rebuild also.
However if you fly on a dirt or grass field, you need to do more often. If you live at sea level and where you would usually have issues with rust, then I would say once a year or maybe once every two years depending on how much you fly. Reality is bearing are pretty cheap. Its usually the rear bearing that is a problem and the front bearing due to the fact its sealed rarely gets bad. However I usually will replace both front and rear bearing when I cahnge them out. No sense in having to take the engine apart again....for a $12 front bearing.
Ceramics are not recommended. I have tried them in both YS 4 strokes and the larger 2 stroke pattern engines. They don't work that well. The higher heat will cause the cage to come apart. Yes the balls will not rust, but if the balls don't stay in the race they do you little good.
I had a buddy that was using them on the OS 140RX and EFI engines. He was going through them quite often like 20-30 flights....they just could not handle the abuse of the Pattern application. I tried then in a YS 140DZ and the temps were too high for the cage. It melted and the balls beat the inside the of the engine to heck.
So ceramics are not recommended for this application.
Troy Newman
Team YS
However if you fly on a dirt or grass field, you need to do more often. If you live at sea level and where you would usually have issues with rust, then I would say once a year or maybe once every two years depending on how much you fly. Reality is bearing are pretty cheap. Its usually the rear bearing that is a problem and the front bearing due to the fact its sealed rarely gets bad. However I usually will replace both front and rear bearing when I cahnge them out. No sense in having to take the engine apart again....for a $12 front bearing.
Ceramics are not recommended. I have tried them in both YS 4 strokes and the larger 2 stroke pattern engines. They don't work that well. The higher heat will cause the cage to come apart. Yes the balls will not rust, but if the balls don't stay in the race they do you little good.
I had a buddy that was using them on the OS 140RX and EFI engines. He was going through them quite often like 20-30 flights....they just could not handle the abuse of the Pattern application. I tried then in a YS 140DZ and the temps were too high for the cage. It melted and the balls beat the inside the of the engine to heck.
So ceramics are not recommended for this application.
Troy Newman
Team YS
